There are various different refrigeration systems for wind turbines known in the field. The following documents are examples of these systems:
WO 00/68570 shows an offshore wind turbine which cools the nacelle by means of a liquid circulated through the tower, transferring the heat to the sea water.
WO 01/06121 and WO 2004/016945 show the use of air circuits for cooling the nacelle. The circuits may be open or closed, with the heat exchanger being the wall of the tower or a conventional ventilation system.